1. Field of the Invention
The present invention relates to an automatic storage system and an automatic storing method in which a carrier for holding a plurality of plate-like works, such as wafers processed in a semiconductor device manufacturing process and reticles for an exposure machine, is accommodated into a container box, and the container box is taken into and taken out of a storage unit.
2. Description of Related Art
In a semiconductor device production line, with an advanced fine patterning and an elevated integrated density of a semiconductor device, in order to prevent dust from being deposited on a wafer, which is a work, to a possible maximum extent, it is a general practice that just until the wafer is actually processed by a manufacturing apparatus in the production line, a wafer carrier for holding wafers is accommodated in a container box so that the wafer is shielded from the outside air. Further, in order to avoid dusts generated from a human body, the opening and closing of the container box and the conveying of the wafer carrier are automated so that the intervention of a human being is avoided. Reticles for an exposure machine, which must be similarly protected from dust deposition, are storage-controlled similarly to the above case. The following description will be limited to the wafer for simplification of the description.
FIG. 1 is a diagrammatic perspective view for illustrating one example of the prior art automatic storage system and automatic storing method. In the prior art, a method for take-in and Lake-out to a storage unit is such that, for example, as shown in FIG. 1, a wafer carrier 6 for holding wafers which have been processed in a preceding processing step is accommodated in a container box 1 and is kept in a storage unit 8 until a next processing is conducted. In order to perform the next processing, after the container box 1 is carried out from the storage unit 8, the wafer carrier 6 is taken out from the container box 1, and then, conveyed by a carrier car 11 to a next manufacturing apparatus, and transferred to a station of the manufacturing apparatus.
Further, the wafer carrier 6, which has received the wafer processed by the manufacturing apparatus, is conveyed to the storage unit 8 by the carrier car 11, and then, transferred to a station before a take-in port 13 of the storage unit 8. Thereafter, the wafer carrier 6 is accommodated in the container box 1, and then, fed into the storage unit 8, so that it is moved to and kept on a predetermined shelf in the storage unit 8 by a not-shown stacker crane.
In addition, when the wafer carrier which holds the processed wafers and which is kept in the storage unit 8 is to be conveyed into another storage unit for a next process, the container box accommodating the wafer carrier therein is taken out from the storage unit 8 by the stacker crane and moved to a station before a take-out port 14. Thereafter, a cover 3 is removed by an opening/closing mechanism 7, so that the wafer carrier 6 is exposed. Furthermore, the wafer carrier 6 is transferred to a bed of the carrier car 11 by a robot arm of the carrier car 11, and then, is conveyed to the next process.
At the same time as the wafer carrier starts to be conveyed, the opening/closing mechanism 7 operates to put the cover 3 on a table 2 to assemble an empty container box. The empty container box thus assembled is picked up by a fork of the stacker crane provided within the storage unit 8, and moved from the take-out port 14 into the storage unit 8 and then located on a predetermined shelf.
As mentioned above, the wafer carrier 6 conveyed for a relatively short time is conveyed in an exposed condition, since possibility of deposition dust is small. On the other hand, the wafer carrier 6 staying in the storage unit 8 for a long time is kept in the storage unit 8 in such a condition that the wafer carrier is accommodated in the container box to prevent the dust from being deposited on the wafers.
Recently, however, the semiconductor devices have an inclination toward many-kind small-production 1 as typified by a custom IC (integrated circuit) so that the number of wafers included in one lot decreases. For example, there has appeared the case that only an extremely small number of wafers, for example, one to three wafers, are accommodated in one wafer carrier. Because of this circumstance, the following problems have been encountered in the above mentioned prior art automatic storage system.
A first problem is that: When a small lot of ICs are manufactured, since the number of wafers held in one wafer carrier decreases, the processing time of the manufacturing apparatus per one wafer carrier becomes extremely short. As a result, the number of conveying opportunities of the wafer carrier per a unit time increases, and therefore the, capability of the automatic storage system is reduced. In order to overcome the reduction of the capability of the automatic storage system, it becomes necessary to increase the number of the storage units. However, since the space between the manufacturing devices is limited, it is not possible to increase the number of the storage units.
A second problem is that: Since an operating time is required for the stacker crane to move the empty container box between the take-in port and the shelf and between the take-out port and the shelf, the conveying time within the storage unit becomes long while the conveying time of the wafer carrier is short. As a result, wafer carriers are backed up congest before the storage unit, and the, possibility that dust is deposited on wafers left in the exposed condition, increases with the result that ? significant defect occurs in quality.
A third problem is that because of the above mentioned congestion, the number of wafers for which a necessary processing has not been completed in a given step, increases with the result that the manufacturing capability drops and the lead time is deteriorates. In addition, the rate of operation in the manufacturing apparatus drops, and the production efficiency lowers.
Accordingly, it is an object of the present invention to provide an automatic storage system and an automatic storing method which have overcome the above mentioned problems of the prior art.
Another object of the present invention is to provide an automatic storage system and an automatic storing method, capable of taking in and taking out container boxes, without increasing the number of storage units and without congestion of carriers for holding works.
The above and other objects of the present invention are achieved in accordance with the present invention by an automatic storage system so configured that a container box for accommodating a box-like carrier which is conveyed by a carrier car and which holds a plurality of plate-like works arranged in one direction, is received for a temporary storage and then the carrier is taken out from the container box and moved to the carrier car, the automatic storage system comprising a storage unit having an inlet/outlet port through which the container box is taken in and out and a plurality of shelves on which the container box is put, a stacker crane traveling within the storage unit to and from the inlet/outlet port and for putting the container box on the shelf and picking up the container box from the shelf, an opening/closing mechanism for opening and closing the container box disposed before the inlet/outlet port, and a control means operating on the basis of a previously set take-in/take-out schedule for container boxes, for taking in and out the container box and for causing an empty container box to stay before the inlet/outlet port.
In addition, the shelf for receiving the empty container box is preferred to be ensured near to the inlet/outlet port within the storage unit. In addition, the works are wafers for semiconductor substrates or reticles for an exposure machine.
According to a second aspect of the present invention, there is provided an automatic storing method for the above mentioned automatic storage system, comprising the steps of causing the carrier conveyed to the inlet/outlet port in accordance with the above mentioned previously set take-in/take-out schedule, to be accommodated into the empty container box previously disposed before the inlet/outlet port, keeping the container box which has accommodated the carrier therein, in the storage unit and thereafter moving another container box kept in the storage unit to the inlet/outlet port, opening the other container box to Take out the carrier in the other container box, and causing the other container box which has become empty, to stay before the inlet/outlet port.
According to a third aspect of the present invention, there is provided an automatic storing method for the above mentioned automatic storage system, comprising the steps of moving the container box kept in the storage unit in accordance with the above mentioned previously set take-in/take-out schedule, to the inlet/outlet port, opening the container box to take out the carrier in the container box, causing the container box which has become empty, to stay before the inlet/outlet port, and causing another carrier conveyed to the inlet/outlet port, to be accommodated into the container box which has become empty, and keeping the container box which has accommodated the other carrier in the storage unit.
The above and other objects, features and advantages of the present invention will be apparent from the following description of preferred embodiments of the invention with reference to the accompanying drawings.